Method of producing dimethylnonanals



United States Patent METHOD OF PRODUCING DIMETHYL- NONANALS CarlBordenca, Birmingham, Ala., assignor to Newport Industries, Inc.,Pensacola, Fla., a corporation of Delaware No Drawing. Application May14, 1953,

Serial No. 355,191 I 5 Claims. or. 260-604 This invention relates to amethod of producing 11- carbon aldehydes, and more particularly4,8-dimethylnonanal.

It is well known that the pyrolysis of certain terpenes leads to theformation of other terpenes which occur naturally only to a smallextent. For example, the pyrolysis of alpha-pinene yields allo-ocimeneand alphaand beta-pyronenes. Allo-ocimene occurs naturally in the oilfrom the leaves of Ocimum basilicum Linn., Ocimum gratissimum Linn. andHamoranthus flavescens.

The pyrolysis of beta-pinene yields predominantly myrcene, which occursnaturally in a number of essential oils especially Verbena oil. Theformulas of myrcene, allo-ocimene, and alphaand beta-pyronenes arerepresented as follows:

CHl l Alpha-pyronene Beta-pyronene I have now found that these terpenepyrolysis products serve as valuable starting materials in theproduction of ll-carbon aldehydes, such as 4,8-dimethylnonanal. Thesealdehydes can be used as such or as intermediates, or can be reduced togive the corresponding alcohol, or oxidized to give the correspondingacid. The dimethylnonanol and dimethylnonanoic acid are useful in themaking of esters which, in turn, can be used in making plasticizers,lubricants and detergents.

It is therefore an important object of this invention to provide amethod for making ll-carbon aldehydes and particularly4,8-dimethylnonanal.

Other and further important objects of this invention will becomeapparent from the following description and appended claims.

In accordance with the method of my present invention, any of theforegoing terpene pyrolysis products, or a mixture of one or more ofthem is subjected to hydroformylation in order to convert these terpenehydrocarbons into the corresponding C-ll aldehydes. The hydroformylationis carried out with the use of a mixture of carbon monoxide andhydrogen, commonly referred to as synthesis gas, under pressure and atan elevated temperature.

The following example will serve to illustrate a preferred embodiment ofmy invention.

Example.--Starting with allo-ocimene ture of carbon monoxide andhydrogen was charged in to a pressure of 4000 p. s. i. and the vesselheated with shaking to 135 C. A maximum pressure of 5500 p. s. i. wasattained at that temperature, followed by pressure reduction in thecourse of 2 hours to 3000 p. s. i. Distillation of the reaction massgave a 70% yield of 4,8

dimethylnonanal based upon the allo-ocimene used as starting material. Afraction analyzing 92% aldehyde boiled at 94-5 C./ 10 mm. Hg and had anindex of refraction, n of 1.4340 and a specific gravity, d4 of 0.834.The 2,4-dinitrophenylhydrazone melted at 69- 72 C.

In the hydroformylation step, the composition of the mixture of carbonmonoxide and hydrogen may be varied considerably, but the 1:1 molarratio commonly used in carrying out the 0x0 reaction has been found mostsatisfactory. The temperature is preferably maintained at less than 200C., with from to C. as the optimum range. Other temperature and pressureconditions and other catalysts than those specifically mentioned in theexample can be used provided they are favorable to the formation of thecorresponding aldehyde with reasonably good yield.

Myrcene can be subjected to hydroformylation under conditions similar tothose given in the example to give 4,8-dimethylnonanal. A simple proofof the structure of aldehyde obtained from myrcene and allo-ocimene wasatforded through comparison of the acid obtained by oxidation of thealdehyde, and 4,8-dimethylnonanoic acid of known structure obtained fromcitral by the following series of reactions:

H: Ottrnl 3,7-dimethyl-l oetanol KCN 1-bromo3,7-d1methyloetane Hi04,8-dimethylnonanitrlle 4,8-dimethylnonanoie acid Amid es and anilidesof the acids were found to have similar properties. Comparison ofinfrared absorption spectra showed the acids to be the same.

When alphaor beta-pyronene is used as the starting material andsubjected to hydroformylation under the same conditions as given forallo-ocimene in the example, ll-carbon aldehydes are formed thatcorrespond to tetramethyl cyclohexyl aldehydes.

I claim as my invention:

1. The method of preparing a dimethylnonanal, which comprises subjectinga terpene selected from the group consisting of allo-ocimene and myrcenein the presence of a hydroformylation catalyst to hydroformylation at anelevated temperature under 200 C. to produce 4,8- dimethylnonanal andrecovering the same.

2. The method of preparing a dimethylnonanal, which comprises subjectinga terpene selected from the group consisting of allo-ocimene and myrceneto the action of carbon monoxide and hydrogen at a temperature of from125 to 150 C. and in the presence of a cobalt hydroformylation catalystuntil an aldehyde having the formula C11H22O has been produced andrecovering said aldehyde.

3. The method of preparing a dimethylnonanal, which comprises subjectinga terpene selected from the group consisting of .allo-ocimene andmyrcene to the action of carbon monoxide and hydrogen at a temperatureof from 125 to 150 C. and in the presence of cobalt carbonyl until analdehyde having the formula CnHzzO has been produced and recovering saidaldehyde.

4. The method of preparing 4,8-dimethylnonanal, which comprisessubjecting a terpene selected from the group consisting of allo-ocimeneand myrcene to the action of carbon monoxide and hydrogen insubstantially a 1:1 ratio, under pressure and at an elevated temperatureunder 200 C. in the presence of a cobalt hydroformylation catalyst untilthe starting terpene has beensubstantially converted into4,8-dimethylnonanal and recovering the latter.

5. In the process of making 4,8-dimethylnonanal, the

step which comprises subjecting va terpene selected from 10 the groupconsisting of myrcene and a1lo-ocimene to the action of carbon monoxideand hydrogen at an elevated temperature under 200 C. in the presence ofcobalt carbonyl under pressure and temperature conditions favor-References Cited in the file of this patent UNITED STATES PATENTS2,437,600 Gresham Mar. 9, 1948 2,462,448 Whitman Feb. 22, 1949 2,686,206Cerveny Aug. 10, 1954 2,688,591 Hill Sept. 7, 1954 2,701,816 Buchne'r'eta1. .4 Feb. 8, 1955 FOREIGN PATENTS 493,493 Belgium -5. Feb. 15, 1950OTHER REFERENCES Groggins: Unit Processes in'Organic Synthesis, pp. 560

able to hydroformylation toproduce 4,8-dimethylnonanal. 16 and 561, MCGBook 1952'

1. THE METHOD OF PREPARING A DIMETHYLNONANAL, WHICH COMPRISES SUBJECTINGA TERPENE SELECTED FROM THE GROUP CONSISTING OF ALLO-OCIMENE AND MYRCENEIN THE PRESENCE OF A HYDROFORMYLATION CATALYST TO HYDROFORMYLATION AT ANELEVATED TEMPERATURE UNDER 200*C. TO PRODUCE 4,8DIMETHYLNONANAL ANDRECOVERING THE SAME.